Description Of Operating Sequence - Panasonic NN-J993 Service Manual

NN-J993
5 DESCRIPTION OF
OPERATING SEQUENCE
5.1. Variable power cooking
control
HIGH VOLTAGE INVERTER POWER SUPPLY (U) controls
output power by the signal from Digital programmer Circuit
(DPC). Power relay 2 stays on while 1000W to 300W selection
but the inverter drive signal to control it's output power 150 W
and 100 W will be ON-OFF controlled.
NOTE: The ON/OFF time ratio does not correspond with
the percentage of microwave power since approximately 2
seconds are required for heating of magnetron filament.
5.2. Defrost
When auto weight defrost is selected and the start Pad is
tapped:
1. The digital programmer circuit determines the power level
and cooking time to complete cooking and indicates the
operating stage in the display window. Table shows the
corresponding cooking
categories.
2. When cooking time in the display window has elapsed, the
oven turns off automatically by a control signal from the digital
programmer circuit.
5.3. Convection Grill Cooking
Control
The digital programmer circuit controls the ON-OFF time of the
heater in order to control oven cavity temperature.
1. After the start pad is tapped with the desired Bake-Broil
program set, an high level signal comes out Micro-Computer
circuit and is applied to gate of triacs, D222 and D223.
2. When triacs turns on, power source voltage is applied the
heater and the heater turns on.
3. When the oven temperature reaches the set temperature,
the digital programmer circuit senses the temperature through
oven temp sensor and stops supplying high level signal to the
triacs and the heater turns off.
4. After the heater turns off, the oven temperature will continue
increasing a while and then decrease as shown in Figure.
When the oven temperature drops below the set temperature,
the digital programmer circuit senses the signal and starts
supplying an high level signal to the trialc again.
time for respective serving by
Defrost
12